FTTH PON Splitting Ratio and Level

As the diagram described, consisting of an Optical Line Terminal (OLT) that is located in the Central Office (CO), the optical network with the optical power splitter and finally, the Optical Network Unit (ONU) as the Customer Premises Equipment (CPE). During the deployment of fiber to the home passive optical network (FTTH-PON), usually, we will face some physical access network design problems.

A Common PON Splitting Level Application

Splitting Ratio Principle and Solution

Optical splitter, also known as beam splitter, is one kind of integrated waveguide optical power distribution device based on a quartz substrate. A fiber splitter is one of the most important passive components in the whole FTTH network system. There are two types of splitters in our current FTTH application, their splitting ratio principle are as following:

1. FBT SPLITTER makes two (two or more) fibers removed the coating layer gather in a certain way, stretched to both sides under the heating zone at the same time, form a double cone’s special waveguide structure finally for getting a different splitting ratio via controlling length of the fiber torsion angle and stretch.
2. PLC SPLITTER is a micro-optical element using photolithographic techniques to form optical waveguide at medium or semiconductor substrate for realizing branch distribution function.

FTTH PON Single Splitting application

Based on our EPON/GPON project experience, two main splitting ratio solutions as following:

• When the splitting ratio is 1:32, your current network can receive qualified fiber optic signal in 20Km.
• If your distance between OLT and ONU is small, like in 5Km, you can also consider about 1:64.

Splitting Level

PON is a point-to-multipoint fiber optical network with no active elements in the signal’s path. It consists of a single, shared optical fiber connecting a service provider’s central office (CO) to a passive splitter, which can accommodate multiple optical connections with customers.

The PON splitting may be achieved by single splitting or by multiple/complex splitting (two-level) distributed splitting. The splitter of single splitting demultiplexes a downstream signal into, for example, 32 subscriber streams. Accordingly, the PON access network with single splitting forms a double-star topology with the first star at the CO and the second star at the splitter.

1. Single splitting is, between the OLT to ONU only existed a single splitter. 
2. Two-level Splitting is, between the OLT to ONU existed two splitters in series.
3. Multi-level splitting is, between the OLT to ONU existed multiple splitters in series

FTTH PON Two-level Splitting Application

The Single Splitting solution is usually used in crowded city center or town areas, in order to reduce cost and easy to maintain the optical distributed network (ODN) nodes.

In the other hand, Two-level and Multi-level Splitting solution is used in curb or village places, to cover widely ODN (optical distributed network) nodes, conserve resources and save the money.

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